1. Field of the Invention
The present invention relates to a substrate processing apparatus for performing a substrate processing process.
2. Description of the Prior Art
Conventionally, as one of processes for manufacturing a semiconductor device such as dynamic random access memory (DRAM), a substrate processing process for forming a thin film on a substrate is performed. Such a substrate processing process is performed by using a substrate processing apparatus including a process chamber configured to accommodate substrates which are horizontally positioned and arranged in multiple stages, a process gas supply nozzle configured to supply a process gas to the process chamber, and an exhaust line configured to exhaust the process chamber. A substrate holding tool in which a plurality of substrates are held is loaded into the process chamber, and while exhausting the process chamber through the exhaust line, a gas is supplied to the process chamber through the process gas supply nozzle, so as to make the gas flow through the substrates for forming thin films on the substrates.
However, in the above-described substrate processing process, process gas supplied to the process chamber may flow to a region where substrates are not stacked (for example, a region higher or lower than a region where the substrates are stacked) instead of flowing between the substrates. In this case, the amount of process gas supplied to the substrates is decreased to lower the film-forming rate or in-surface or inter-substrate processing uniformity.
In addition, a process gas flowing to a region where substrates are not stacked may be attached to the inner wall of the process chamber and form a thin film which generate contaminates.
Particularly, in the region where substrates are not stacked, if the inner wall of the process chamber has a low temperature, a thin film may be easily formed on the inner wall. In addition, if the inner wall of the process chamber has a low temperature, a thin film may not be easily removed by gas cleaning (dry cleaning).